Okay, we are tasked with adding 6174 and 3404. Let's begin!

Step 1: We'll start by adding the digits 4 & 4 in column 1 and get 8.

Step 2: We'll start by adding the digits 7 & 0 in column 2 and get 7.

Step 3: We'll start by adding the digits 1 & 4 in column 3 and get 5.

Step 4: We'll start by adding the digits 6 & 3 in column 4 and get 9.

So, 6174 + 3404 = 9578.

